Elastic electric contact terminals are used to electrically and elastically connect electrically conductive objects and conductive patterns of a printed circuit board (PCB) in a state where the electrically conductive objects and the conductive patterns are individually provided, or face each other.
Such elastic electric contact terminals may be used as electric connecting terminals, ground connecting terminals, and electromagnetic interference (EMI) shield members.
To this end, elastic electric contact terminals may be required to have excellent electrical conductivity and high elastic resilient force, and to uniformly disperse pressure applied thereto. In addition, elastic electric contact terminals may be required to have low electrical contact resistance with an object, and be installed thereon reliably and economically. To this end, a surface mounting process using vacuum pickup, and a reflow soldering process using solder cream may be sequentially performed to install elastic electric contact terminals on a conductive pattern of a PCB
A solderable elastic electric contact terminal is disclosed in Korean Patent Registration No. 10-1001354 applied by the applicant of the present invention, in which a non-foaming elastic core includes a through hole along the longitudinal direction thereof to appropriately and elastically resist pressure applied from the upper side thereof.
However, when the height of the solderable elastic electric contact terminal is significantly smaller than the width thereof, for example, the solderable elastic electric contact terminal has a width of 2.5 mm or smaller, and a height of 1 mm or smaller, the following problems may occur.
First, the through hole has an oval shape with a large width-to-height ratio, in order to decrease pressure applied to the elastic core and increase the resilient force thereof. In this case, the elastic core may sags, which jeopardizes flatness of the top thereof for vacuum pickup, and decreases force for entirely supporting the elastic electric contact terminal so as to decrease the resilient force thereof.
In addition, since the through hole has a large width-to-height ratio, when pressure is applied to the elastic core from the upper side thereof, the laterally middle portion of the elastic core is recessed more easily than both side portions thereof are, thus degrading contact efficiency between the elastic electric contact terminal and an object.
In addition, it may be difficult to massively produce bilateral symmetric elastic cores having a through hole with a large width-to-height ratio.
In addition, when the elastic core having a through hole with a large width-to-height ratio is heated and pressed from the upper side thereof, that is, when a reliability test is performed thereon, the top and bottom walls of the elastic core defining the through hole may be adhered to each other.